FIELD OF THE INVENTION
The present invention relates to an ultraviolet ray projector. More particularly, it relates to an ultraviolet ray projector for hardening a paint for a short time by irradiating ultraviolet rays on a coated surface of an ultraviolet ray-curable paint such as various resin coating compositions.
2. DESCRIPTION OF THE PRIOR ARTS
A soft synthetic resin sheet having long length and width is laid on a floor of a passenger train and buildings. The floor sheet has disadvantages to form cigarette spot which is caused by a burning cigarette end and to form heel-mark which is black trace caused by strong friction of rubber heel.
In order to overcome these disadvantages, it has been proposed to coat a transparent acrylic resin on the surface of the floor sheet and to harden the surface of the floor sheet.
The former is effective for preventing the heel-mark but is not effective for preventing the cigarette spot. Moreover, when it is coated in thick thickness, it takes a long time for drying the coated layer. Accordingly, the former has not been practically applied.
The latter is relatively effective for preventing the cigarette spot, but it has fatal disadvantages as a floor sheet because of slippery and inferior feeling. Accordingly, the latter has not been practically applied.
An ultraviolet ray-curable paint which has been recently developed, can be coated in thick thickness and can be hardened for a short time by irradiating ultraviolet rays. The resulting coated layer is soft but prevents both of the heel-mark and the cigarette spot. Accordingly, the application of the ultraviolet ray-curable paint is significantly effective for overcoming the disadvantages of the heel-mark and the cigarette spot.
The ultraviolet ray-curable paint is a paint which is reacted by an irradiation of ultraviolet rays to harden from liquid to solid. The hardening is performed only for a short time such as several tens seconds. Accordingly, it is remarkably advantageous for a continuous surface treatment of the floor sheet.
When the coated floor sheet is laid on a floor of a building, the coated floor sheet is bonded with an adhesive composition. It is important to consider a treatment of joints between the floor sheets laid on the floor. In usual, a welding processing with a welding rod has been applied to prevent an immersion of water and to prevent a joint opening caused by contraction of the floor sheet. In the case of the floor sheet coated with the ultraviolet ray-curable paint, the welding processing is also required. After the welding processing, it is necessary to coat the ultraviolet ray-curable paint on the joint and to harden it by irradiating ultraviolet rays.
It has not been considered to apply an ultraviolet ray-curable paint in such manner, and accordingly an ultraviolet ray projector for hardening the ultraviolet ray-curable paint coated on joints of the floor sheets has not been considered.